Nice to hear of this sort of altruism. Good show.
Your friend has overt AIDS, and not being on treatment probable very high viral load and maximally infectious. Oral to genital transmission still very unlikely, but I would avoid any sex at all, or only with condoms. With only oral and fingering, your risk is very low, but probably not zero.
If you'd like to extend your altruism to others, see if you can convince your friend about the danger he poses to sex partners and encourage condom use, at least for anal sex, assuming economic realities prevent him from stopping sex altogether. As things stand now, he's probably at the peak of danger to others.
HIV is rarely if ever transmitted mouth to penis. Nobody can say the risk is truly zero, but there has never once been a proved case -- and that's despite people having herpes or other sores in the mouth, or the penile partner having genital herpes. So you you were not at risk from the oral sex events.
I don't understand your comments about his oxygen mask. HIV is not caught by providing that sort of care to AIDS patients. If your hand are going to come into contact with body fluids, standard precautions are to wear protective gloves -- but for the mask, it would be sufficient to just wash your hands or use an alcohol gel (like Purel). Anyway, your own urethra of course would not be at risk from this sort of contact.
Finally, knowing your partner has HIV, perhaps you know more about hs infection. If he is on anti-HIV drugs and has a low viral load, he probably isn't infectioius and none of these comments was risky at all. If you don't know, ask; and in the future, always ask these things before having sex with someone suspected to have HIV.
But for now, no worries at all. You're a compassionate person to be willing to help care for this friend. Good show!